Mitsubishi Lancer Evolution X. Manual - part 165

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-125

STEP 7. Resistance measurement at A-05 ASC-ECU 
connector
(1) Disconnect the ASC-ECU connector, connect special tool 

ASC check harness (MB991997) to the harness-side 
connector, and then measure the resistance at the special 
tool connector side.
NOTE: Do not connect the special tool ASC check harness 
(MB991997) to ASC-ECU.

(2) Disconnect the fusible link No.27.
(3) Resistance between the terminal No.32 and the body 

ground.

OK: No continuity

Q: Is the check result normal?

YES : Replace the fusible link No.27. Then go to Step 11.
NO :  The short circuit may be present in the power supply 

circuit. Repair the wiring harness between the A-05 
ASC-ECU connector terminal No.32 and the fusible 
link No.27, and then replace the fusible link No.27. 
Then go to Step 11.

STEP 8. Voltage measurement at A-05 ASC-ECU connector
(1) Disconnect the connector, connect the special tool ASC 

check harness (MB991997) to the wiring harness-side 
connector, and measure the voltage at the special tool 
connector side.
NOTE: Do not connect the special tool to ASC-ECU.

(2) Measure the voltage between the terminal No. 32 and the 

body ground.

OK: Battery positive voltage

Q: Is the check result normal?

YES : Go to Step 9.
NO :  The open circuit may be present in the power supply 

circuit. Repair the wiring harness between the A-05 
ASC-ECU connector terminal No.32 and the fusible 
link No.27. Then go to Step 11.

AC400817EO

ASC-ECU

MB991997

A-05 ASC-ECU 
harness connector

Check harness

AC400817CN

ASC-ECU

MB991997

A-05 ASC-ECU 
harness connector

Check harness

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-126

STEP 9. Resistance measurement at A-05 ASC-ECU 
connector
(1) Disconnect the connector, connect the special tool ASC 

check harness (MB991997) to the wiring harness-side 
connector, and measure the voltage at the special tool 
connector side.
NOTE: Do not connect the special tool to ASC-ECU.

(2) Measure the resistance between the terminal No. 16 and 

the body ground as well as between the terminal No. 47 
and the body ground.

OK: Continuity exists (2 Ω or less)

Q: Is the check result normal?

YES : Go to Step 10.
NO :  An open circuit may be present in the ground circuit. 

Repair the wiring harness between the A-05 
ASC-ECU connector terminal No.16 and the body 
ground, and between the A-05 ASC-ECU connector 
terminal No.47 and the body ground. Then go to Step 
11.

STEP 10. Check whether the DTC is reset.
Q: Is DTC C2104 set?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-298

.) Then go to Step 11.

NO :  Intermittent malfunction. (Refer to GROUP 00 − How 

to Cope with Intermittent Malfunction 

P.00-15

.)

STEP 11. Check whether the DTC is reset.
Q: Is DTC C2104 set?

YES : Return to Step 1.
NO :  This diagnosis is complete.

AC400817CO

ASC-ECU

MB991997

A-05 ASC-ECU 
harness connector

Check harness

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-127

DTC C1073: Faulty motor drive circuit

CAUTION

• If there is any problem in the CAN bus lines, an incor-

rect diagnostic trouble code may be set. Prior to this 
diagnosis, diagnose the CAN bus lines.

• Whenever the ECU is replaced, ensure that the CAN 

bus lines are normal.

• When the hydraulic unit (integrated with ASC-ECU) is 

replaced, always perform the calibration of steering 
wheel sensor, G and yaw rate sensor, brake fluid pres-
sure sensor, cut valve, and inlet valve.(Refer to 

P.35C-287

, 

P.35C-289

, 

P.35C-294

, and 

P.35C-295

.)

.

ASC-ECU

AC804602

Motor Power Supply Circuit

MOTOR 
POWER 
SUPPLY

FUSIBLE
LINK

26

AC708948

Connector: A-05

A-05 (B)

AB

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-128

CIRCUIT OPERATION

• ASC-ECU contains the power supply circuit (terminal No. 1) 

for the motor. The pump motor is energized by the pump 
motor switch, which is incorporated in ASC-ECU.

• The pump motor switch in ASC-ECU is turned off at all 

times unless during the motor solenoid valve check per-
formed when the vehicle is started.

• ASC-ECU activates the pump motor by turning on the ECU 

built-in pump motor switch.

.

DTC SET CONDITIONS

If the variation of pump motor switch voltage drop during or 
after the pump motor operation becomes larger than the speci-
fied value, the pump motor operation is stopped and this DTC 
is set.

.

PROBABLE CAUSES

Current trouble

• Fusible link malfunction
• Damaged wiring harness and connectors
• Abnormality in battery or generator
• ASC-ECU malfunction

Past trouble

• Perform the diagnosis with a particular emphasis on the wir-

ing harness and connector failures in the ASC-ECU motor 
power supply circuit (A-05 ASC-ECU connector terminal 
No. 1) and in the ground circuit (A-05 ASC-ECU connector 
terminal No. 16 and No.47). For diagnosis procedures, refer 
to How to Treat Past Trouble (GROUP 00 − How to Use 

Troubleshooting/Inspection Service Points 

P.00-16

).

DIAGNOSIS

Required Special Tools:

• MB991958 Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)
• MB991827 M.U.T.-III USB Cable
• MB991910 M.U.T.-III Main Harness A

• MB991997: ASC check harness

STEP 1. Using scan tool MB991958, diagnose the CAN bus 
lines.
Using scan tool MB991958, diagnose the CAN bus lines.
Q: Is the check result normal?

YES : Go to Step 3.
NO :  Repair the CAN bus lines (Refer to GROUP 54C − 

CAN Bus Diagnosis table 

P.54C-15

). On completion, 

go to Step 2.